1. Field of the Invention
The present invention relates to a novel sodium tripolyphosphate having a high rate of hydration, to detergent compositions comprised thereof, and to sprayable slurries for the preparation of such compositions by atomization.
2. Description of the Prior Art
It is known to this art that the preparation of detergents includes a first step designed to convert anhydrous sodium tripolyphosphate (TPP), in as quantitative a manner as is possible, into hexahydrated sodium tripolyphosphate, in the aqueous detergent medium comprising the other constituents of the detergent.
The slurry resulting from the first step is then atomized in an atomization tower to provide the detergent in powder form. Such quantitative conversion of anhydrous TPP into hexahydrated TPP is necessary in order to ensure that the detergent users do not experience the disadvantages of the detergent forming lumps, and an excessive amount of heat being evolved, as would be the result in the case of incomplete hydration of the anhydrous TPP.
Therefore, the first property required of TPP is that it should be capable of undergoing hydration as rapidly and as quantitatively as possible.
The second property required is a viscosity which permits the slurry produced from the TPP to be pumped and sprayed.
The aforenoted hydration properties are closely linked to the quality of the TPP (proportion of pyrophosphate and polyphosphate), and other characteristics such as grain size, proportion of phase I, and the like.
Thus, in the case of a TPP destined for the production of a detergent powder by atomization, the choice of the TPP is generally in favor of a TPP having a high proportion of phase II, which makes it possible to reduce viscosity, but unfortunately to the detriment of the rate of hydration.
European patent application No. 81/13221 (EP 70 216), filed July 6, 1981, and corresponding to copending application, Ser. No. 395,114, filed July 6, 1982 and assigned to the assignee hereof, relates to the thermal and/or chemical treatment of a fluid dispersible phase, e.g., a aqueous solution of monosodium and disodium orthophosphates, by means of a dispersing gaseous phase, characterized by, in succession and without interruption;
(i) establishing a vertically descending current of axially extending, axially symmetrical helical flow of a hot gaseous phase;
(ii) separately establishing a second phase liquid current of coaxially downwardly vertically extending, rectilinear continuous jet stream of the, e.g., aqueous orthophosphate solution noted above;
(iii) maintaining said currents of said first hot gaseous and said second liquid, e.g., orthophosphate phases physically separate from each other;
(iv) circulating and directing said currents which comprise the respective plural phases to a low pressure zone of restricted flow passage with respect to said helical flow;
(v) at said zone of restricted flow passage, converging and intimately, homogeneously admixing said plural currents, and atomizing into a multitude of droplets, and entraining/dispersing and thermally dehydrating said rectilinear jet stream liquid orthophosphate current as unit volumes within said helical spinning current of hot gas; and
(vi) at the zone of convergence of the respective phases the first phase helical flow of hot gas is such that the momentum thereof is at least 100 times greater than the momentum of the second phase, coaxial rectilinear flow of the orthophosphate solution being thermally dehydrated.
Thus, said thermal dehydration is advantageously homogeneously conducted via flash treatment in a zone of plug-flow of the atomized droplets of feed solution and completed in an isothermal zone, with such treatment being both substantially isothermic and chemically homogeneous, in a region of homogeneous flow in the sense of distribution of the residence times.
And French application No. 81/13223, corresponding to pending application, Ser. No. 305,600, filed July 6, 1982, also assigned to the assignee hereof, features a novel sodium orthophosphate having a Na/P ratio of essentially 5/3, which has but a single crystalline phase and a novel and characteristic X-ray diffraction pattern.
Such a product may be obtained by carrying out the process described above, under particular and specific operating conditions. For a more detailed description of the applicable methodology, see copending application, Ser. No. 395,798, filed July 6, 1982, also assigned to the assignee hereof.
More particularly, as claimed in said French application No. 81/13221, and copending application, Ser. No. 395,114, it is possible to produce a novel tripolyphosphate which displays zero solidification or caking in a quiescent solvent medium.
Advantageously, the TPP does not comprise any insoluble fraction. It exhibits a surprising behavior in regard to solubilization, in consideration of the proportion of phase I and the granulometry thereof.